A flash memory is a type of EEPROM that allows multiple memory locations to be erased or written in one programming operation. In lay terms, it is a form of rewritable memory chip that, unlike a Random Access Memory chip, saves its content without maintaining a power supply.
An ordinary EEPROM only allows one location at a time to be erased or written, meaning that flash memory can operate at higher effective speeds when the system uses it to read and write to different locations at the same time. All types of flash memory and EEPROM wear out after a certain number of erase operations, due to wear on the insulating oxide layer around the charge storage mechanism used to store data.
Flash memory is non-volatile, which means that it stores information on a silicon chip in a way that does not need power to maintain the information in the chip. In addition, flash memory offers fast read access times and solid-state shock resistance. These characteristics explain the popularity of flash memory for applications such as storage on battery-powered devices like mobile phones and personal digital assistants.
Common flash memory parts (individual internal components or “chips”) range widely in capacity from kilobits to hundreds of megabits each. Toshiba and SanDisk have developed a NAND flash chip capable of storing 8 gigabits (1 gigabyte) of data using MLC (multi-level cell) technology, capable of storing 2 bits of data per cell. In September 2005, Samsung Electronics, by far the world's largest manufacturer of NAND flash with ˜40% of bit market share, announced that it had developed the world's first 16 gigabit NAND flash memory chip. With the introduction of Samsung's 16 gigabit chips came the iPod nano, a flash device available in 2 GB and 4 GB capacities, which use two 1 gigabyte Toshiba chips and two 2 gigabyte Samsung chips respectively, according to the autopsies done by Ars Technica and Inpress Direct. Up to date NAND spot pricing is available. In efforts to focus on increasing capacities, 32 MB and smaller capacity flash memory has been largely discontinued, and 64 MB capacity flash memory is being phased out.
Nowadays, the memory is commonly used in memory cards, USB flash drives, MP3 players, digital cameras and mobile phones. Usually, it is available in capacities of 64 M, 128 M, 256 M, 512 M, 1 G and 2 G in a single memory chip. However, when the memory chip is manufacturing, there could be bad blocks (usually the capacity of a sector) that cannot reliably save data due to a physical flaw of damaged format markings. Possibly, a memory chip is manufactured in capacities of 1 G, wherein it also contains bad blocks about 200 M. Therefore, this memory chip can't be applied for 1 G flash memory.
Therefore, it needs to provide a flash memory of single chip and a method for utilizing the same, which divides the flash memory into at least two logical memories in different capacities for facilitating to optimize the memory space thereof, and can rectify those drawbacks of the prior art and solve the above problems.